Method and apparatus for automatic calibration of ocular kappa angle

Abstract

The application discloses a method and device for automatically calibrating an eyeball Kappa angle, and the method comprises the following steps: collecting a gaze parameter of an eyeball of a user by using a single camera and double infrared light sources arranged in a head-mounted device; calculating a corneal curvature center and an optical axis of the eyeball of the user according to the gaze parameter; calculating a Kappa angle according to the corneal curvature center and the optical axis; wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eyeball of the user; and calculating the visual axis of the eyeball of the user according to the optical axis and the Kappa angle. The application omits the explicit calibration process of a traditional line-of-sight tracking method, and can implicitly complete the calibration of the Kappa angle in a tracking stage, so that the line-of-sight of the user can be accurately and efficiently tracked automatically.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of visual tracking, in particular to a method and device for automatically calibrating Kappa angle of eyeball. BACKGROUND

[0002] In the field of visual tracking, the gaze tracking method uses existing electronic, mechanical, optical and other methods to detect the gaze direction or fixation point of the human eye. It is widely used in cognitive process research, auxiliary driving, psychology and psychiatry research, market marketing and advertisement, virtual reality, human-computer interaction and other fields. In addition, in recent years, VR technology has made great progress, and VR and AR wearable devices are constantly updated, providing users with various immersive experiences, and gaze tracking technology has gradually become an important part of VR technology. The gaze tracking method can reduce the parallax between the real world and the virtual world, and can provide users with a more realistic and natural VR application experience. However, it is difficult to cope with the free movement of the head and the dramatic changes in lighting conditions, and the calibration procedure is cumbersome and inconvenient for the subject, and it is easy to make mistakes when the subject does not see the expected place due to fatigue or lack of concentration.

[0003] Therefore, how to automatically track the user's gaze has become a technical problem that technicians in the field need to solve. SUMMARY

[0004] The purpose of the present application is to provide a method and device for automatically calibrating Kappa angle of eyeball, which can accurately and efficiently automatically track the user's gaze.

[0005] According to one aspect of the present application, a method for automatically calibrating Kappa angle of eyeball is provided, the method comprising:

[0006] Using a single camera and double infrared light sources arranged in the head-mounted device, the gaze parameters of the user's eyeball are collected;

[0007] According to the gaze parameters, the corneal curvature center and the optical axis of the user's eyeball are calculated;

[0008] According to the corneal curvature center and the optical axis, the Kappa angle is calculated; wherein the Kappa angle is the included angle between the visual axis and the optical axis of the user's eyeball;

[0009] According to the optical axis and the Kappa angle, the visual axis of the user's eyeball is calculated.

[0010] Optionally, the calculation of the corneal curvature center of the user's eyeball according to the gaze parameters comprises:

[0011] A three-dimensional coordinate system is created, and the optical center of the single camera is set as the origin of the three-dimensional coordinate system; The point is set as the origin of the system three-dimensional coordinate system;

[0012] In the system three-dimensional coordinate system, according to the coordinate positions of the two infrared light sources and and the parameters of the single camera, the coordinate positions of two imaging points and presented on the imaging surface of the single camera are calculated; wherein the two infrared light sources and are reflected on the two reflection points and on the outer surface of the cornea of the user's eyeball, and then pass through the optical center point and intersect with the imaging surface at the two imaging points and ; According to the coordinate positions of the optical center point of the single camera in the system three-dimensional coordinate, the coordinate positions of the two infrared light sources

[0013] and and the coordinate positions of the two imaging points and , the corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated.

[0014] Optionally, according to the coordinate positions of the optical center point of the single camera in the system three-dimensional coordinate, the coordinate positions of the two infrared light sources and and the coordinate positions of the two imaging points and , the corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated, including:

[0015] The corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated according to the following formulas:

[0016] ;

[0017] ;

[0018] ; ​​

[0019] ;

[0020] ;

[0021] wherein, let , at this time, , and the h represents the modulus value of the distance from the corneal curvature center point to the optical center point of the single camera.

[0022] Optionally, the calculating the optical axis of the eyeball of the user according to the gaze parameter comprises:

[0023] The coordinate position of the pupil center point of the user in the three-dimensional coordinate system of the system is calculated according to the following formula, and the optical axis of the eyeball of the user is calculated according to the pupil center point and the corneal curvature center point:

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] wherein, the light ray reaches the point on the outer edge of the pupil of the eyeball of the user after being refracted by the point on the outer surface of the cornea of the eyeball of the user, and and are the incident angle and the exit angle in the refraction process, respectively

[0030] and are the refractive index of the light ray in the air and the refractive index of the light ray inside the cornea, respectively;

[0031] point is any point on the edge of the pupil of the eyeball of the user, and the distance from any point on the edge of the pupil to the pupil center point is the same, j∈[1,200]

[0032] is the unit vector in the incident direction in the refraction process;

[0033] For Point and The modulus value of the distance between the points.

[0034] Optionally, the Kappa angle is calculated according to the corneal center of curvature and the optical axis, comprising:

[0035] The left eye rotation axis and the left eye rotation angle are calculated according to the left eye optical axis collected in the i-th time and the left eye optical axis collected in the (i+1)-th time, and the left eye rotation matrix is calculated according to the left eye rotation axis and the left eye rotation angle ;

[0036] The right eye rotation axis and the right eye rotation angle are calculated according to the right eye optical axis collected in the i-th time and the right eye optical axis collected in the (i+1)-th time, and the right eye rotation matrix is calculated according to the right eye rotation axis and the right eye rotation angle ;

[0037] The left eye coordinate system of the user is established; wherein the left eye corneal center of curvature is set as the origin of the left eye coordinate system, and the left eye visual axis direction collected in the i-th time is set as the axis of the left eye coordinate system; The right eye coordinate system of the user is established; wherein the right eye corneal center of curvature is set as the origin of the right eye coordinate system, and the right eye visual axis direction collected in the i-th time is set as the

[0038] axis of the right eye coordinate system; The Kappa angle of the left eye and the Kappa angle of the right eye of the user are calculated according to the following formula:

[0039] ;

[0040] ;

[0041] ;

[0042] ;

[0043] ;

[0044] ;

[0045] wherein, and respectively represent the horizontal component and the vertical component of the Kappa angle of the left eye of the user;

[0046] respectively represent the horizontal component and the vertical component of the Kappa angle of the right eye of the user; ​represents a unit vector in the direction of the visual axis of the i-th acquisition in the left eye of the user, ;

[0047] represents a normal vector of the plane formed by the two visual axes at the (i+1)-th acquisition in the left eye of the user;

[0048] represents a unit vector in the direction of the visual axis of the (i+1)-th acquisition in the left eye of the user;

[0049] represents a unit vector in the direction of the visual axis of the (i+1)-th acquisition in the right eye of the user.

[0050] Optionally, after the Kappa angle is calculated according to the corneal curvature center and the optical axis, the method further comprises:

[0051] Step 1: forming a 0th generation population according to N groups of initial Kappa angles calculated according to N acquisition data { }, and setting the 0th generation population as a target population; wherein each individual is a four-dimensional vector formed by the left eye Kappa angle and the right eye Kappa angle calculated according to the i-th acquisition data; ;

[0052] Step 2: inputting each individual in the target population into a preset objective function in turn, and setting the individual corresponding to the minimum value of the objective function as a target individual;

[0053] wherein the objective function is: ;

[0054] is the distance between the two visual axes in the i-th acquisition data, and ;

[0055] Step 3: judging whether a preset stopping iteration rule is reached, if yes, executing Step 5, if not, executing Step 4; wherein the preset stopping iteration rule is that the minimum value of the objective function is less than a first preset threshold, or the generation number of the target population reaches a second preset threshold;

[0056] Step 4: updating the target population according to a preset differential evolution algorithm to obtain a tth generation population, setting the tth generation population as the target population, and re-executing Step 2;

[0057] Step 5: Forming the final Kappa angle of the user's eyeball according to the target individual in the latest generation population.

[0058] Optionally, the preset stopping iteration rule comprises:

[0059] The boundary vector is obtained according to the following formula :

[0060] ;

[0061] Wherein, ;

[0062] ,

[0063] , , is an individual randomly selected from the first generation population;

[0064] The mutation operator is a real constant factor;

[0065] The intermediate vector is formed according to the following formula :

[0066] ;

[0067] Wherein,

[0068] is a random real number

[0069] is a random integer

[0070] is a random integer

[0071] The individual in the t-th generation population is formed according to the following formula :

[0072] .

[0073] In order to achieve the above purpose, the application further provides a device for automatically calibrating the Kappa angle of the eyeball, which comprises:

[0074] The acquisition module is used for acquiring the gaze parameter of the user's eyeball by using a single camera and double infrared light sources arranged in the head-mounted device.

[0075] ​​​an optical axis module configured to calculate a corneal curvature center and an optical axis of the eyeball of the user according to the gaze parameter;

[0076] an included angle module configured to calculate a Kappa angle according to the corneal curvature center and the optical axis; wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eyeball of the user;

[0077] a visual axis module configured to calculate the visual axis of the eyeball of the user according to the optical axis and the Kappa angle.

[0078] To achieve the above object, the present application further provides a computer device, which specifically comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the steps of the method for automatically calibrating the Kappa angle of the eyeball when executing the computer program.

[0079] To achieve the above object, the present application further provides a computer readable storage medium, which stores a computer program, and the computer program implements the steps of the method for automatically calibrating the Kappa angle of the eyeball when executed by a processor.

[0080] The method and device for automatically calibrating the Kappa angle of the eyeball provided by the present application, by using a single camera and double infrared light sources arranged in the head-mounted device, collect the gaze parameter of the eyeball of the user, calculate the corneal curvature center and the optical axis of the eyeball of the user according to the gaze parameter, calculate the Kappa angle according to the corneal curvature center and the optical axis, and calculate the visual axis of the eyeball of the user according to the optical axis and the Kappa angle, without the need for the user to gaze at the calibration point at a specific time, improve the continuity of the line-of-sight tracking and the user experience, and omit the explicit calibration process of the traditional line-of-sight tracking method, so that the calibration of the Kappa angle is implicitly completed in the tracking stage, and the line-of-sight of the user is accurately and efficiently tracked automatically. BRIEF DESCRIPTION OF DRAWINGS

[0081] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments, and are not meant to limit the present application. Furthermore, the same reference numerals in different drawings are intended to represent the same components throughout the several drawings. In the drawings:

[0082] Figure 1 An optional flowchart of the method for automatically calibrating the Kappa angle of the eyeball provided for example one;

[0083] Figure 2 A reflection diagram of the double infrared light sources on the outer surface of the cornea provided for example one;

[0084] Figure 3 A schematic diagram of the refraction of light on the outer surface of the cornea is provided for Embodiment One;

[0085] Figure 4 A schematic diagram of a user observing a screen is provided for Embodiment One;

[0086] Figure 5 A schematic diagram of the eye coordinate system is provided for Embodiment One;

[0087] Figure 6 A schematic diagram of the rotation axis movement is provided for Embodiment One;

[0088] Figure 7 A schematic diagram of the three-dimensional eye model is provided for Embodiment One;

[0089] Figure 8 A flowchart of the line-of-sight estimation is provided for Embodiment One;

[0090] Figure 9 A schematic diagram of the line-of-sight landing point is provided for Embodiment One;

[0091] Figure 10 An alternative schematic diagram of the device for automatically calibrating the Kappa angle of the eye is provided for Embodiment Two;

[0092] Figure 11 An alternative schematic diagram of the hardware structure of the computer device is provided for Embodiment Three. DETAILED DESCRIPTION

[0093] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0094] Embodiment One

[0095] The embodiments of the present application provide a method for automatically calibrating the Kappa angle of the eye, which is applied to a head-mounted device, such as a virtual reality device. Figure 1 As shown in the figure, the method specifically comprises the following steps:

[0096] S101: Using a single camera and double infrared light sources arranged in the head-mounted device, the gaze parameters of the user's eye are collected.

[0097] In this embodiment, the user wears a head-mounted 3D gaze tracking device, which includes multiple light sources, a display screen, and a single camera. When the user gazes at an object while wearing the device, gaze parameters of the user's eyes are acquired by detecting the image of the user's eyes. These gaze parameters include at least the position information of two infrared light sources, the position information of two imaging points on the imaging surface of the single camera, and the position information of the gaze point on the display screen.

[0098] S102: Calculate the corneal curvature center and optical axis of the user's eyeball based on the gaze parameters.

[0099] Specifically, by utilizing the imaging rules of infrared light reflected from the outer surface of the cornea and refracted at the edge of the pupil in a single camera, the corneal radius, corneal curvature center, and pupil center of the user's eyeball are calculated. The optical axis is formed by the straight line connecting the corneal curvature center and the pupil center.

[0100] Specifically, the step S102 of calculating the corneal curvature center of the user's eyeball based on the fixation parameters includes:

[0101] Step A1: Create a three-dimensional coordinate system for the system and set the optical center of the single camera. The point is set as the origin of the three-dimensional coordinate system of the system;

[0102] Step A2: In the three-dimensional coordinate system of the system, based on the dual infrared light sources and Based on the coordinates of the location and the parameters of the single camera, the dual infrared light source is calculated. and Two imaging points presented on the imaging plane of the single camera and The coordinate position; wherein, the dual infrared light source and Two reflection points on the outer surface of the cornea of ​​the user's eyeball and After reflection, and simultaneously passing through the optical center The point intersects the imaging plane at two imaging points. and ;

[0103] Step A3: Based on the optical center of the single camera in the three-dimensional coordinates of the system. The coordinates of the point, the dual infrared light source and The coordinates of the two imaging points and The user's corneal radius is calculated based on the coordinates of the location. and corneal curvature center The coordinate position of the point in the system three-dimensional coordinate system.

[0104] In the embodiment, as shown in Figure 2 The two infrared light sources and When reflected by the outer surface of the cornea, the optical center point of the single camera is set as the origin of the system three-dimensional coordinate system, and the infrared light sources After being reflected by the reflection points on the outer surface of the cornea , the imaging points on the imaging surface of the single camera are the optical center points of the single camera. After being reflected by the reflection points on the outer surface of the cornea , the imaging points on the imaging surface of the single camera are the optical center points of the single camera. According to the coordinate positions of the two infrared light sources and , the coordinate position of the optical center point of the single camera, and the coordinate positions of the two imaging points and , the corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated.

[0105] Further, the corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated, comprising:

[0106] The corneal radius and the coordinate position of the corneal curvature center point of the user in the system three-dimensional coordinate system are calculated according to the following formula:

[0107] According to the law of reflection of light, the incident angle is equal to the exit angle. When the two infrared light sources are reflected by the outer surface of the cornea, there is the following relationship between the unit vectors on the straight line where the incident light, the exit light and the normal line are located:

[0108] ;

[0109] ;

[0110] In the reflection of light, the incident light, the normal line and the exit light are coplanar, and two sets of reflections form a reflection plane. Both of the two reflection planes contain the most , The intersection line of the two reflection planes, so ​The cross product of two plane normals can be expressed as:

[0111]

[0112] The expression of the corneal center can be simplified as , and the corneal center can be expressed as: ; h represents the corneal center point to the optical center of the single camera point distance modulus value;

[0113] The distance between the corneal center point and the reflection point and are all corneal radius values:

[0114]

[0115] The cornea can be equivalent to a spherical surface, and the coordinate equation of the spherical surface is as follows:

[0116]

[0117] By combining the above equations (1)-(6), the corneal radius and the coordinate position of the corneal center point in the three-dimensional coordinate system of the system can be obtained.

[0118] Specifically, the step S102 of calculating the optical axis of the user's eyeball according to the gaze parameter comprises:

[0119] As shown in Figure 3 , the pupil edge point on the corneal outer surface after refraction is , the pupil is approximated as a circular plane inside the cornea, and due to the different propagation speeds of light in the eyeball and the outside air, the pupil plane undergoes a refraction on the corneal surface before imaging in the camera. The refractive indices of light in air and inside the cornea are and , respectively, and the incident angle and the exit angle in the refraction process are and , respectively, which satisfy the following relationship:

[0120] (7);

[0121] The incident light, the normal and the exit light in the refraction process are coplanar, and the refraction geometric model of the pupil edge point satisfies the following equation:

[0122] ​​​ ;

[0123] In particular, and is a known quantity, take 1, take 1.34, and let the unit vector in the direction of incidence in the refraction process be: (9);

[0124] then where is the distance between the point and the center of the pupil. Since the pupil is approximated as a circular plane, the distance between the edge point of the pupil and the center of the pupil is the same, so there is: ; where,

[0125] , the point is any point on the edge of the pupil of the user's eyeball, and the distance between any point on the edge of the pupil and the center of the pupil is the same, a, j ∈ [1, 200] The optical axis of the eyeball passes through the corneal curvature center point and the center of the pupil

[0126] point, and is perpendicular to the pupil plane, so the vector and the vector on the pupil plane are perpendicular to each other:

[0127] ;

[0128] The above equations (7)-(11) are combined to calculate the coordinate position of the center of the pupil point of the user in the three-dimensional coordinates of the system, and the optical axis is calculated according to the center of the pupil point and the corneal curvature center point.

[0129] S103: Calculate the Kappa angle according to the corneal curvature center and the optical axis; the Kappa angle is the angle between the visual axis and the optical axis of the user's eyeball.

[0130] In this embodiment, as described above, the intersection of the left eye visual axis and the right eye visual axis with the screen is coincident when the user observes the screen. The Kappa angle of the left eyeball and the Kappa angle of the right eyeball of the user are calculated according to the corneal curvature center and the optical axis of the left eyeball and the right eyeball of the user respectively; the Kappa angle is the angle between the visual axis and the optical axis of the user's eyeball. Figure 4

[0131] ​​​Specifically, the step S103 of calculating the Kappa angle based on the corneal curvature center and optical axis includes:

[0132] Step B1: Calculate the left eye rotation axis and left eye rotation angle based on the left eye optical axis of the i-th acquisition and the left eye optical axis of the (i+1)-th acquisition, and calculate the left eye rotation matrix based on the left eye rotation axis and left eye rotation angle. ;

[0133] Step B2: Calculate the right eye rotation axis and right eye rotation angle based on the right eye optical axis of the i-th acquisition and the right eye optical axis of the (i+1)-th acquisition, and calculate the right eye rotation matrix based on the right eye rotation axis and right eye rotation angle. ;

[0134] Step B3: Establish the user's left eye coordinate system; wherein, the center of curvature of the left eye cornea is... Set the origin of the left eye coordinate system, and set the left eye visual axis direction of the i-th acquisition as the origin of the left eye coordinate system. axis;

[0135] Step B4: Establish the user's right eye coordinate system; wherein, the center of curvature of the right eye cornea is... Set as the origin of the right eye coordinate system, and set the right eye visual axis direction of the i-th acquisition as the origin of the right eye coordinate system. axis;

[0136] Step B5: Calculate the Kappa angle of the user's left eye and right eye using the following formulas simultaneously:

[0137] In this embodiment, as Figure 5 As shown, the eye coordinate system places the corneal center Defined as the origin of the coordinate system, and the view axis direction as... Axis. At the initial gaze position. axis, axis, Axis and world coordinate system axis, axis, The axes correspond to parallel axes. When the gaze direction changes, the human eye moves in accordance with Listing's law, and the eye coordinate system rotates according to Listing's law after the gaze direction changes.

[0138] In the eye coordinate system, the Kappa angle is calculated using the horizontal component. and vertical components It is represented by [the term]. Therefore, the unit vector along the optical axis in the eye coordinate system [is used]. It can be represented as:

[0139] ;

[0140] At the initial eye position, the world coordinate system is parallel to the eye coordinate system, so at this time... It is also a unit vector along the optical axis in the world coordinate system. The visual axis vector at different viewing positions is obtained through a transformation matrix. Obtained from the initial gaze position:

[0141] ;in , Let these represent the unit vectors along the visual axis at the current and initial fixation positions of the user's left and right eyes, respectively. .

[0142] like Figure 6 As shown, according to Listing's law, the movement of the eyeball from the initial gaze direction to any other gaze direction can be described by a single rotation about the normal to the plane formed by the visual axes at the initial and final gaze positions. The center of rotation... Translate to the origin of the world coordinate system ,at this time exist On the axis. (See diagram) and These are the unit vectors along the optical axis at the initial and final positions, respectively. The rotation axis of the eye movement from the initial fixation position l to the fixation position 2. yes and The common perpendicular lines, because exist On the axis, so it can be determined exist On a plane. And since the eyeball moves within a certain angular range, it can be known that... exist The component in the direction is not zero, so we can assume . It can also be seen as Around Therefore, obtained by rotation:

[0143] ;

[0144] Assumption and The quantity is known. and Angle between It refers to the angle of eyeball rotation. Given the axis of rotation and the angle of rotation, then from... arrive rotation matrix It can be obtained by the Rodriguez formula:

[0145] ;

[0146] When calculating the Kappa angle of the left eye of the user and the Kappa angle of the right eye of the user , at any moment of natural fixation of the subject, the visual axes of the left and right eyes intersect at a point. By using the optical axis and the corneal center of curvature collected at each fixation moment, the rotation matrix of the left eye and the right eye is calculated respectively by the above formula , the rotation matrix of the left eye and the right eye is represented respectively as and and , and then the unit vector of the visual axis direction of the (i+1)th collection of the left eye of the user and the unit vector of the visual axis direction of the (i+1)th collection of the right eye of the user .

[0147] (16);

[0148] (17);

[0149] At any fixation moment, the visual axes of the left and right eyes intersect in space at a point, and at this moment, the two visual axes form a plane. The normal of the plane can be expressed as :

[0150] (18);

[0151] A vector is constructed from the left corneal center to the right corneal center:

[0152] (19);

[0153] Since the visual axis passes through the corneal center, the vector is perpendicular to the normal of the plane formed by the left and right visual axes :

[0154] (20);

[0155] wherein and respectively represent the horizontal component and the vertical component of the Kappa angle of the left eye of the user;

[0156] respectively represent the horizontal component and the vertical component of the Kappa angle of the right eye of the user; ​

[0157] represents a unit vector in the direction of the visual axis of the i-th acquisition in the left and right eye of the user, ;

[0158] represents the normal of the plane formed by the two visual axes at the (i+1)-th acquisition in the left and right eye of the user;

[0159] The above equations (16)-(20) are combined to calculate the Kappa angle of the left eye and the Kappa angle of the right eye of the user in the ideal case.

[0160] Specifically, after the Kappa angle is calculated according to the corneal curvature center and the optical axis in the step S103, the method further comprises:

[0161] Step C1: Forming the 0th generation population according to the N groups of initial Kappa angles calculated from the N acquisition data { }, and setting the 0th generation population as the target population; wherein each individual is a four-dimensional vector formed by the left eye Kappa angle and the right eye Kappa angle calculated from the i-th acquisition data; ;

[0162] Step C2: Inputting each individual in the target population into a preset objective function in turn, and setting the individual corresponding to the minimum value of the objective function as the target individual;

[0163] Wherein, the objective function is:

[0164] ;

[0165] is the distance between the two visual axes in the i-th acquisition data, and ;

[0166] Step C3: judging whether a preset stopping iteration rule is reached, if yes, executing step C5, if not, executing step C4; wherein the preset stopping iteration rule is that the minimum value of the objective function is less than a first preset threshold, or the generation number of the target population reaches a second preset threshold;

[0167] Step C4: updating the target population according to a preset differential evolution algorithm to obtain the tth generation population, setting the tth generation population as the target population, and re-executing step C2;

[0168] Step C5: Form the final Kappa angle of the user's eyeball according to the target individual in the latest generation population.

[0169] Further, the preset stopping iteration rule comprises:

[0170] Step D1: The mutation of each individual is realized by a differential strategy, and the differential strategy adopted is as follows:

[0171] ;

[0172] Wherein, ;

[0173] ,

[0174] , , is an individual randomly selected from the t-th generation population; the mutation operator is a real constant factor; if goes beyond the boundary, then takes the boundary value. Step D2:

[0175] and are crossed to generate a new vector :

[0176] ;

[0177] Wherein, is the crossover probability is a random real number of ; is a random integer of ;

[0178] Step D3: Form the individual in the t-th generation population according to the following formula :

[0179] .

[0180] According to the above formulas (21)-(25), after completing the above evolution operation, the value of the objective function in the population is iterated again, and the optimal individual in this generation is found. The algorithm ends after completing the maximum evolution generation or finding an individual whose objective function value is less than the set value.

[0181] S104: Calculate the visual axis of the user's eyeball according to the optical axis and the Kappa angle.

[0182] ​In this embodiment, after obtaining the Kappa angle of the user's left eye and the Kappa angle of the user's right eye, the visual axis of the left eye is calculated based on the optical axis and Kappa angle of the user's left eye, and the visual axis of the right eye is calculated based on the optical axis and Kappa angle of the user's right eye, thereby estimating the user's gaze direction in real time.

[0183] like Figure 7 As shown, the axis of symmetry of the eyeball, i.e., the optical axis, passes through the center of the eyeball, the center of corneal curvature, and the center of the pupil. The outer surface of the cornea can be considered as a spherical cross-section with the optical axis as its axis of symmetry, and the eyeball is considered as a curved surface formed by the intersection of two spheres of different sizes. Assuming that the center of corneal curvature coincides with the nodal point of the eyeball (i.e., the optical center of the eyeball, which is located behind the lens in the simplified model), the visual axis (line of sight) is defined as a straight line connecting the fovea and the center of corneal curvature. The angle between the optical axis and the visual axis is also called the kappa angle. The magnitude and direction of this angle vary depending on the individual face and need to be obtained through calibration procedures. Figure 8 As shown, the system in the head-mounted device uses a single camera to capture real-time facial images and processes the real-time images of the eyes within those images to extract features. Based on the internal parameters of the single camera and the dual infrared light sources, combined with the internal structural parameters of the eyeball, the corneal curvature center, corneal radius, and pupil center are calculated, thus constructing a real-time eye coordinate system. Based on multiple sets of real-time eye data parameters, a differential evolution algorithm is used to continuously optimize the kappa angle between the user's left and right eyes. After obtaining the optimal kappa angle, the visual axes of the user's left and right eyes are calculated based on the optical axis and the kappa angle to determine the user's real-time gaze direction.

[0184] The following is a specific test example for calculating the kappa angle using the method described above:

[0185] Subjects at Screen In this case, design uniformly distributed on the screen Coordinate grid points. This generates the virtual subject's gaze. The coordinates of the corneal center and optical axis direction vectors of the two eyes were calculated at the coordinate grid points, and an amplitude of [value missing] was added to the corneal center coordinates. The noise, the amplitude added to the optical axis direction vector is The noise. The estimated line-of-sight point is as follows: Figure 9 As shown, it can be observed that the estimated gaze points show a significant collective downward-right shift compared to the actual gaze points. This is because the calculated kappa angle maintains consistency in the left-right eye error direction in both the vertical and horizontal components, resulting in a consistent deviation direction for the gaze points estimated using this kappa angle. The average deviation distance between the 25 sets of gaze points and the actual gaze points is... This accuracy can satisfy some simple line-of-sight tracking system applications.

[0186] In order to verify the feasibility of the automatic calibration algorithm, a practical system experiment is also conducted. In the experiment, a glasses-type eye tracker is used, which is configured with one infrared camera and eight infrared light sources for the left and right eyes respectively. In the actual calculation of the corneal parameters, only two infrared light sources are used for each eye. The eye tracker is also configured with a front camera for detecting the objects observed by the user. The world coordinate system is the front camera coordinate system. The subject wears the eye tracker and sits in front of a 15.6-inch notebook computer screen at a distance of about 50 cm. The eye tracker is connected to the notebook computer through a USB interface. The program is run, the eye map is collected and image processing is performed, the coordinates of the corneal surface and the pupil edge points are extracted, the corneal curvature center coordinates and the pupil center coordinates are calculated, and the optical axis direction vector is reconstructed. Finally, the value of the kappa angle of the subject's two eyes is calculated by using the automatic calibration method of the differential evolution method, as shown in Table 1:

[0187] Table 1

[0188]

[0189] In the experiment, the four corners of the computer screen are fixed with circular patterns with known radius and screen coordinates. The spatial coordinates of the centers of the four circular patterns can be obtained by taking pictures of them with the front camera, and the screen coordinates can be determined. The real line-of-sight direction can be determined by the coordinates of the fixation points and the corneal curvature center coordinates, and the line-of-sight landing point can be calculated. The error of the line-of-sight landing point calculated by the automatic user calibration algorithm of the differential evolution method is 2.9°.

[0190] In the embodiment, by using a single camera and double infrared light sources arranged in the head-mounted device, the gaze parameters of the user's eyeball are collected; the corneal curvature center and the optical axis of the user's eyeball are calculated according to the gaze parameters; the Kappa angle is calculated according to the corneal curvature center and the optical axis; the visual axis of the user's eyeball is calculated according to the optical axis and the Kappa angle; the user does not need to actively cooperate during user calibration, and the user does not need to fixate on the calibration point at a specific time, which improves the continuity of the line-of-sight tracking process, omits the explicit calibration process of the traditional line-of-sight tracking method, implicitly completes the calibration of the Kappa angle in the tracking stage, realizes accurate and efficient automatic tracking of the user's line-of-sight, and greatly reduces the error of the line-of-sight estimation by using the differential evolution algorithm.

[0191] Embodiment two

[0192] The embodiment of the present application provides a device for constructing a terrain model, as shown in the figure, which specifically comprises the following components: Figure 10 ​

[0193] The acquisition module 1001 is used to acquire the user's eye gaze parameters using a single camera and dual infrared light sources installed in the head-mounted device;

[0194] The optical axis module 1002 is used to calculate the corneal curvature center and optical axis of the user's eyeball based on the gaze parameters;

[0195] Angle module 1003 is used to calculate the Kappa angle based on the corneal curvature center and the optical axis; wherein, the Kappa angle is the angle between the visual axis and the optical axis of the user's eyeball;

[0196] The visual axis module 1004 is used to calculate the visual axis of the user's eyeball based on the optical axis and the Kappa angle.

[0197] Specifically, the optical axis module 1002 is used for:

[0198] Create a three-dimensional coordinate system for the system and place the optical center of the single camera. The point is set as the origin of the three-dimensional coordinate system of the system; in the three-dimensional coordinate system of the system, according to the dual infrared light sources and Based on the coordinates of the location and the parameters of the single camera, the dual infrared light source is calculated. and Two imaging points presented on the imaging plane of the single camera and The coordinate position; wherein, the dual infrared light source and Two reflection points on the outer surface of the cornea of ​​the user's eyeball and After reflection, and simultaneously passing through the optical center The point intersects the imaging plane at two imaging points. and According to the optical center of the single camera in the three-dimensional coordinates of the system. The coordinates of the point, the dual infrared light source and The coordinates of the two imaging points and The user's corneal radius is calculated based on the coordinates of the location. and corneal curvature center The coordinate position of the point in the three-dimensional coordinate system of the system.

[0199] Furthermore, the optical axis module 1002 is also used for:

[0200] The user's corneal radius can be calculated using the following formulas. and corneal curvature center The coordinate position of the point in the three-dimensional coordinate system of the system:

[0201] ;

[0202] ;

[0203] ;

[0204] ;

[0205] ;

[0206] Among them, let ,at this time, And h represents the corneal curvature center. Point to the optical center of the single camera The modulus of the point distance.

[0207] Furthermore, the optical axis module 1002 is also used for:

[0208] The pupil center of the user can be calculated using the following formulas. The coordinate position of the point in the three-dimensional coordinate system, and according to the pupil center. Point and the corneal curvature center The optical axis of the user's eyeball is calculated:

[0209] ;

[0210] ;

[0211] ;

[0212] ;

[0213] ;

[0214] Among them, the light passes through the outer surface of the cornea of ​​the user's eyeball. After refraction, the light reaches the outer edge of the user's pupil. Point, and and These are the incident angle and the exit angle during the refraction process. and These are the refractive indices of light in the air and inside the cornea, respectively. The point is any point on the edge of the pupil of the user's eyeball, and the distance from any point on the edge of the pupil to the center of the pupil is... The points are equidistant, j∈[1, 200] is a unit vector in the direction of incidence in the refraction process; is a unit vector in the direction of incidence in the refraction process; is a unit vector in the direction of incidence in the refraction process; is a unit vector in the direction of incidence in the refraction process.

[0215] Specifically, the included angle module 1003 is configured to:

[0216] calculate a left eye rotation axis and a left eye rotation angle according to the left eye optical axis collected in the i-th time and the left eye optical axis collected in the (i+1)-th time, and calculate a left eye rotation matrix according to the left eye rotation axis and the left eye rotation angle ; calculate a right eye rotation axis and a right eye rotation angle according to the right eye optical axis collected in the i-th time and the right eye optical axis collected in the (i+1)-th time, and calculate a right eye rotation matrix according to the right eye rotation axis and the right eye rotation angle ; establish a left eye globe coordinate system of the user; wherein the left eye globe corneal curvature center is set as the origin of the left eye globe coordinate system, and the direction of the left eye visual axis collected in the i-th time is set as the axis of the left eye globe coordinate system; establish a right eye globe coordinate system of the user; wherein the right eye globe corneal curvature center is set as the origin of the right eye globe coordinate system, and the direction of the right eye visual axis collected in the i-th time is set as the axis of the right eye globe coordinate system; the Kappa angle of the left eye globe and the Kappa angle of the right eye globe of the user are calculated according to the following formula:

[0217] ;

[0218] ;

[0219] ;

[0220] ;

[0221] ;

[0222] wherein, and respectively represent the horizontal component and the vertical component of the Kappa angle of the left eye globe of the user; respectively represent the horizontal component and the vertical component of the Kappa angle of the right eye globe of the user; represents a unit vector in the direction of the visual axis collected in the i-th time in the left eye globe and the right eye globe of the user, ; represents the normal of the plane formed by the two visual axes when collected in the (i+1)-th time in the left eye globe and the right eye globe of the user; represents a unit vector in the direction of the visual axis of the (i+1)th acquisition in the left eye of the user; represents a unit vector in the direction of the visual axis of the (i+1)th acquisition in the right eye of the user.

[0223] Specifically, the device further comprises an error module for:

[0224] Step 1: Form the 0th generation population according to the N groups of initial Kappa angles calculated from the N acquisition data { } and set the 0th generation population as the target population; wherein the individual is a four-dimensional vector formed by the left eye Kappa angle and the right eye Kappa angle calculated from the i th acquisition data; ;

[0225] Step 2: Input each individual in the target population into a preset objective function in turn, and set the individual corresponding to the minimum value of the objective function as the target individual;

[0226] The objective function is: ;

[0227] is the distance between the two visual axes in the i th acquisition data, and ;

[0228] Step 3: Determine whether the preset stopping iteration rule is reached, if yes, execute step 5, if not, execute step 4; wherein the preset stopping iteration rule is that the minimum value of the objective function is less than a first preset threshold, or the generation number of the target population reaches a second preset threshold;

[0229] Step 4: Update the target population according to the preset differential evolution algorithm to obtain the t th generation population, set the t th generation population as the target population, and re-execute step 2;

[0230] Step 5: Form the final Kappa angle of the user's eye according to the target individual in the latest generation population.

[0231] Further, the error module is further used for:

[0232] The boundary vector is obtained according to the following formula:

[0233] ;

[0234] Wherein, ;

[0235] ,

[0236] , , is randomly selected from the population of the t-th generation;

[0237] mutation operator is a real constant factor;

[0238] The intermediate vector is formed according to the following formula :

[0239] ;

[0240] wherein, is a random real number; is a random integer number; The individuals in the population of the t-th generation are formed according to the following formula : :

[0241] .

[0242] Embodiment Three

[0243] The embodiment also provides a computer device, such as a smartphone, a tablet computer, a notebook computer, a desktop computer, a rack server, a blade server, a tower server, or a cabinet server (including a single server or a server cluster composed of multiple servers), which can execute a program. As shown in Figure 11 , the computer device 110 of the embodiment at least includes but is not limited to a memory 1101 and a processor 1102 which can be connected to each other through a system bus. It should be noted that Figure 11 only the computer device 110 with components 1101-1102 is shown, but it should be understood that all the shown components are not required to be implemented, and more or fewer components can be alternatively implemented.

[0244] ​​​The memory 1101 (i.e., a readable storage medium) in the embodiment includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, etc. In some embodiments, the memory 1101 can be an internal storage unit of the computer device 110, such as a hard disk or a memory of the computer device 110. In other embodiments, the memory 1101 can also be an external storage device of the computer device 110, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device 110. Of course, the memory 1101 can include both the internal storage unit and the external storage device of the computer device 110. In the embodiment, the memory 1101 is generally used to store an operating system and various application software installed on the computer device 110. In addition, the memory 1101 can also be used to temporarily store various data that have been output or will be output.

[0245] The processor 1102 can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip in some embodiments. The processor 1102 is generally used to control the overall operation of the computer device 110.

[0246] Specifically, in the embodiment, the processor 1102 is configured to execute a program of an automatic calibration method of an eye Kappa angle stored in the memory 1101, and the program of the automatic calibration method of the eye Kappa angle, when executed, implements the following steps:

[0247] A gaze parameter of an eye of a user is collected by using a single camera and dual infrared light sources arranged in the head-mounted device;

[0248] A corneal curvature center and an optical axis of the eye of the user are calculated according to the gaze parameter;

[0249] A Kappa angle is calculated according to the corneal curvature center and the optical axis; wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eye of the user;

[0250] The visual axis of the eye of the user is calculated according to the optical axis and the Kappa angle.

[0251] The specific embodiment process of the above method steps can be referred to Embodiment One, which will not be repeated here. The processor 1102 can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip in some embodiments. The processor 1102 is generally used to control the overall operation of the computer device 110.

[0252] Embodiment Four

[0253] The embodiment also provides a computer readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card memory (for example, an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, a server, an App application market, etc., which stores a computer program. When the computer program is executed by a processor, the following method steps are implemented:

[0254] A gaze parameter of an eyeball of a user is collected by using a single camera and double infrared light sources arranged in the head-mounted device.

[0255] A corneal curvature center and an optical axis of the eyeball of the user are calculated according to the gaze parameter.

[0256] A Kappa angle is calculated according to the corneal curvature center and the optical axis, wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eyeball of the user.

[0257] A visual axis of the eyeball of the user is calculated according to the optical axis and the Kappa angle.

[0258] The specific embodiment process of the above method steps can be referred to Embodiment One, which will not be repeated here.

[0259] It should be noted that in this document, the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0260] The above embodiment numbers of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0261] Through the above description of the embodiments, those skilled in the art can clearly understand that the above embodiment methods can be realized by means of software and necessary general hardware platform, of course, also can be realized by hardware, but in many cases, the former is a better embodiment.

[0262] The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application, and any equivalent structure or equivalent process conversion, or direct or indirect application in other related technical fields, which are made by using the content of the present application specification and drawings, are also included in the patent protection scope of the present application.

Claims

1. A method of automatically calibrating a Kappa angle of an eye, characterized by, The method is applied to a head-mounted device, and comprises: collecting gaze parameters of eyeballs of a user by using a single camera and double infrared light sources arranged in the head-mounted device; calculating a corneal curvature center and an optical axis of the eyeballs of the user according to the gaze parameters; calculating a Kappa angle according to the corneal curvature center and the optical axis; wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eyeballs of the user; calculating the visual axis of the eyeballs of the user according to the optical axis and the Kappa angle; calculating the corneal curvature center of the eyeballs of the user according to the gaze parameters comprises: create a system three-dimensional coordinate system, and set the optical center of the single camera as the origin of the system three-dimensional coordinate system point In the three-dimensional coordinate system of the system, based on the dual infrared light sources and Based on the coordinates of the location and the parameters of the single camera, the dual infrared light source is calculated. and Two imaging points presented on the imaging plane of the single camera and The coordinate position; wherein, the dual infrared light source and Two reflection points on the outer surface of the cornea of ​​the user's eyeball and After reflection, and simultaneously passing through the optical center The point intersects the imaging plane at two imaging points. and ; the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line connecting the two infrared light sources​​ 2. The method of automatically calibrating ocular kappa angle according to claim 1, wherein, the coordinates of the point of the center of the light of the single camera in the three-dimensional coordinate system of the system the coordinates of the point of the center of the light of the single camera in the three-dimensional coordinate system of the system and the coordinates of the point of the center of the light of the single camera in the three-dimensional coordinate system of the system and the coordinates of the point of the center of the light of the single camera in the three-dimensional coordinate system of the system and the coordinates of the point of the center of the light of the single camera in the three-dimensional coordinate system of the system The corneal radius of the user is calculated simultaneously according to the following formula and the corneal curvature center The coordinate position of the point in the three-dimensional coordinate system of the system: ； ； ； ； ； wherein, let at this time, and h represents the corneal curvature center point to the optical center of the single camera.

3. The method of automatically calibrating ocular kappa angle according to claim 2, wherein, calculating the optical axis of the eyeballs of the user according to the gaze parameters comprises: The user's pupil center is calculated simultaneously according to the following equations The point in the system three-dimensional coordinates, and according to the pupil center The point and the corneal curvature center The user's eye optical axis is calculated ； ； ； ； ； Among them, the light passes through the outer surface of the cornea of ​​the user's eyeball. After refraction, the point reaches the outer edge of the pupil of the user's eyeball. Point, and and These are the incident angle and the exit angle during the refraction process. and n and n2are the refractive indices of light in air and within the cornea, respectively; a point on the pupil edge of the user's eyeball, and the distance from any point on the pupil edge to the pupil center is the same for all points, j e [1, 200] is the unit vector in the direction of incidence for the refraction process; For The point and The modulus of the distance of the point.

4. The method of automatically calibrating ocular kappa angle according to claim 3, wherein, the calculating the Kappa angle according to the corneal curvature center and the optical axis comprises: calculating a left eye rotation axis and a left eye rotation angle according to the left eye optical axis of the i-th acquisition and the left eye optical axis of the (i+1)-th acquisition, and calculating a left eye rotation matrix according to the left eye rotation axis and the left eye rotation angle ; calculating a right eye rotation axis and a right eye rotation angle according to the right eye optical axis of the i-th acquisition and the right eye optical axis of the (i+1)-th acquisition, and calculating a right eye rotation matrix according to the right eye rotation axis and the right eye rotation angle ; establishing a left eyeball coordinate system of the user; wherein the left eyeball corneal curvature center is set as an origin of the left eyeball coordinate system, and the left eye visual axis direction of the i-th acquisition is set as an axis of the left eyeball coordinate system; establishing a right eyeball coordinate system of the user; wherein the right eyeball corneal curvature center is set as an origin of the right eyeball coordinate system, and a right eye visual axis direction of the i-th acquisition is set as an axis of the right eyeball coordinate system; the Kappa angle of the left eyeball and the Kappa angle of the right eyeball of the user are calculated according to the following formula: ； ； ； ； ； wherein, with respectively denote the horizontal and vertical components of the Kappa angle of the left eye ball of the user; respectively denote the horizontal and vertical components of the Kappa angle of the right eye of the user; denotes the unit vector in the direction of the visual axis at the i-th acquisition in the left eye of the user and ; represents a normal to the plane formed by the two visual axes at the (i+1)th acquisition in the left and right eye of the user; denotes the unit vector in the direction of the visual axis at the (i+1)th acquisition in the left eye of the user; denotes the unit vector in the direction of the visual axis at the (i+1)th acquisition in the right eye of the user.

5. The method of automatically calibrating ocular kappa angle according to claim 4, wherein, after the calculating the Kappa angle according to the corneal curvature center and the optical axis, the method further comprises: Step 1: Forming the 0th generation population according to N sets of initial Kappa angles calculated based on N sets of collected data { } and setting the 0th generation population as the target population; wherein the individual is a four-dimensional vector formed according to the left eye Kappa angle and the right eye Kappa angle calculated based on the i-th set of collected data; ; Step 2: input each individual in the target population into a preset target function in turn, and set the individual corresponding to the minimum value of the target function as a target individual; wherein the objective function is: ; di is the distance between the two viewing axes in the i-th data acquisition; Step 3: determine whether a preset stopping iteration rule is reached, if yes, execute Step 5, and if no, execute Step 4; wherein the preset stopping iteration rule is that the minimum value of the target function is less than a first preset threshold, or the generation number of the target population reaches a second preset threshold; Step 4: update the target population according to a preset differential evolution algorithm to obtain a t-th generation population, set the t-th generation population as the target population, and re-execute Step 2; Step 5: form a final Kappa angle of the eyeballs of the user according to the target individual in the latest generation population.

6. The method of automatically calibrating ocular kappa angle according to claim 5, wherein, the preset stopping iteration rule comprises: The boundary vector is obtained according to the following formula : ； wherein , ; ， , , It is random from the () Individuals selected from the population; Variation operator is a real constant factor; The intermediate vector is formed according to the following equation : ； wherein, for the cross probability For a random real number; is a random integer; and is a random integer; and The individuals in the tth generation are formed according to the following formula : 。 7. A device for automatically calibrating the Kappa angle of the eyeball, characterized in that, The device is applied to a head-mounted device, and comprises: a collecting module configured to collect gaze parameters of eyeballs of a user by using a single camera and double infrared light sources arranged in the head-mounted device; an optical axis module configured to calculate a corneal curvature center and an optical axis of the eyeballs of the user according to the gaze parameters; an included angle module configured to calculate a Kappa angle according to the corneal curvature center and the optical axis; wherein the Kappa angle is an included angle between a visual axis and the optical axis of the eyeballs of the user; a visual axis module configured to calculate the visual axis of the eyeballs of the user according to the optical axis and the Kappa angle; The optical axis module is further configured to create a system three-dimensional coordinate system, and set the optical center of the single camera as an origin of the system three-dimensional coordinate system. point of the system three-dimensional coordinate system; In the three-dimensional coordinate system of the system, based on the dual infrared light sources and Based on the coordinates of the location and the parameters of the single camera, the dual infrared light source is calculated. and Two imaging points presented on the imaging plane of the single camera and The coordinate position; wherein, the dual infrared light source and Two reflection points on the outer surface of the cornea of ​​the user's eyeball and After reflection, and simultaneously passing through the optical center The point intersects the imaging plane at two imaging points. and ; the coordinates of the point of intersection of the optical axis of the single camera and the line of intersection of the two infrared light sources the coordinates of the point of intersection of the optical axis of the single camera and the line of intersection of the two infrared light sources and the coordinates of the point of intersection of the optical axis of the single camera and the line of intersection of the two infrared light sources and the coordinates of the point of intersection of the optical axis of the single camera and the line of intersection of the two infrared light sources and the coordinates of the point of intersection of the optical axis of the single camera and the line of intersection of the two infrared light sources 8. A computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method in any one of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executable on the processor to implement the steps of the method in any one of claims 1 to 6.

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